Food transport system

ABSTRACT

The present invention provides a food transport system comprising a conveyor including a controller that controls the movement of plates of food around the conveyor and determines the circulation time of each plate of food, a food heater and food cooler. The controller automatically diverts individual plates of food to the food heater if they require reheating and automatically diverts individual plates of food to the food cooler if they require cooling.

FIELD OF THE INVENTION

The present invention is directed to food transport systems, and more particularly food transport systems including automated food heating and food cooling.

Background Of The Invention Conveyor-based food movement systems are known in the art. Typically, food is placed onto the conveyor in a food preparation area and moved to a pick-up or dining room area. For example, such conveyor-based food movement systems have been used to transport food in sushi restaurants.

Turning our attention to U.S. Pat. No. 6,554,106, the patent discloses a food transport system for use with sushi and the like. This invention includes the ability to identify the particular type of food product passing by on the conveyor and, if that product is old, redirect the food product to be disposed of. The reference however, does not include the concept of heating or cooling the food product as it comes by.

U.S. Pat. No. 6,431,318 also discloses a sushi conveying system. This system includes a reader which is able to interpret the type of sushi passing by on the conveyor and then uses that information to instruct the kitchen to prepare types of food which are not currently on the conveyor system in the desired quantity. However, the system does not include the ability to heat or cool the food products on the conveyor.

U.S. Pat. No. 5,419,410 also includes a food conveying system. This system monitors the type of food, although for purposes of directing it to the right location. In this patent, the customer orders the product and the product which is then delivered directly to them by means of a smart conveyor system. It does not include heating or cooling of the food once it is placed on the conveyor system.

One disadvantage of these types of food conveyor systems is that they do not include automated heating of hot-served foods once they are placed onto the conveyor. Another disadvantage is that these types of food conveyor systems do not include automated cooling of cold-served foods once they are placed onto the conveyor

In view of the above, there exists a need for a food conveyor systems that permits automated heating of hot-served foods and automated cooling of cold-served foods once they are placed onto the conveyor.

SUMMARY OF THE INVENTION

The present invention provides a conveyor-based food transport system, wherein food is placed onto the conveyor in a food preparation area or kitchen and moved to a pick-up or dining room area. Advantageously, the system includes a food heater for heating food and drinks that require re-heating during circulation. The system further comprises a food cooler for cooling food and drinks that require re-cooling during circulation. According to one embodiment, the food heater is a steamer and the food cooler is a freezer.

The conveyor-based food transport system further comprises a system for identifying the individual food and drinks being moved by the conveyor. The conveyor includes a plurality of mounting stations adapted to receive plates and disposed at predetermined intervals along the conveyor. Each mounting station includes a unique machine-readable identifier (e.g., a barcode or similar) specifying the type of food or drink to be mounted thereon. Additionally, each plate includes a unique machine-readable identifier specifying the type of food or drink to be served thereon. In some embodiments, mounting stations are not provided.

One or more scanners preferably are disposed at predetermined locations along the conveyor. Scanner obtains information from the machine-readable identifiers concerning the type of food or drink disposed on each mounting station and plate. One or more temperature sensors (e.g., infrared sensors) are also disposed at predetermined locations along the conveyor. Temperature sensor determines the current temperature of each plate. Food or drinks that require heating are automatically directed toward food heater and food or drinks that require cooling are automatically directed toward food cooler. In some embodiments, a controller is provided for determining the circulation time of each plate of food and diverting foods to the food heater, food cooler or trash area based upon predetermined circulation time limits.

One aspect of the present invention involves a food transport system comprising a conveyor including a controller that controls the movement of plates of food around the conveyor and determines the circulation time of each plate of food, a food heater and food cooler. The controller automatically diverts individual plates of food to the food heater if they require reheating and automatically diverts individual plates of food to the food cooler if they require cooling.

A further aspect of the present invention involves a food transport system comprising a conveyor including a plurality of mounting stations for mounting individual plates of food. The conveyor comprises a controller that controls the movement of food around the conveyor, a food heater and a temperature sensor that senses the temperature of the individual plates of food. The controller includes a temperature monitor that checks whether individual plate of food fall within a predetermined temperature range and diverts individual plates of food to the food heater if they have a temperature that is below the predetermined temperature range.

Another aspect of the present invention involves a food transport system comprising a conveyor including a plurality of mounting stations for mounting individual plates of food. The conveyor comprises a controller that controls the movement of food around the conveyor, a food cooler and a temperature sensor that senses the temperature of the individual plates of food. The controller includes a temperature monitor that checks whether individual plates of food are below a predetermined temperature. Individual plates of food having a temperature that is above the predetermined temperature are diverted to the food cooler.

to the food cooler if they These and other features and advantages of the present invention will be appreciated from review of the following detailed description of the invention, along with the accompanying figures in which like reference numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a food transport system in accordance with the principles of the present invention;

FIG. 2 is a block diagram of the food transport system of FIG. 1;

FIG. 3 is a cross-sectional view of the food transport system of FIG. 1 taken along line 3-3;

FIGS. 4A and 4B are front and rear views, respectively, of a food heater suitable for use with the food transport system of the present invention; and

FIGS. 5A and SB are front and rear views, respectively, of a food cooler suitable for use with the food transport system of the present invention.

DETAILED DESCRIPTION

In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s).

Referring to FIG. 1, a food transport system 10 in accordance with the principles of the present invention will now be described. Food transport system 10 comprises a conveyor 20 including a plurality of mounting stations 25 for mounting individual plates 30 of food and drinks, a food heater 40, individual machine-readable identifiers 50 disposed on each plate 30, individual machine-readable identifiers 55 disposed on each mounting station 25, a scanner 60 for reading the machine-readable identifiers 50, 55, and a temperature sensor 70 for determining the temperature of each plate. One suitable type of temperature sensor is an infrared sensor. Scanner 60 preferably obtains information from machine-readable identifiers 50,55 concerning the type of food or drink disposed on each mounting station 25.

According to some embodiments of the present invention, mounting stations 25 are not employed, and the individual plates are positioned directly on top of conveyor 20. In these embodiments, a plurality of scanners 60 are disposed at predetermined intervals around the conveyor. Scanners 60 obtain information from individual machine-readable identifiers 50 concerning the type of food disposed on each plate 30, as well as the present location of the each plate 30 on the conveyor 20.

In a preferred embodiment, the food heater comprises a steam heater. However, as would be understood by those of ordinary skill in the art, the heater may comprise any other type of food heater, including, but not limited to, a microwave oven, one or more heat lamps, a roaster without departing from the scope of the present invention. According to some embodiments, the food transport system further comprising a food cooler 100, wherein individual plates 30 of food are diverted to the food cooler for cooling.

With further reference to FIG. 1, food transport system 10 is disposed within the interior of a restaurant, which includes a dining area 110 and kitchen 120. A plurality of dining tables 130 are arranged within the dining area to accommodate the patrons of the restaurant. The dining area and kitchen may be separated by a partition 140, for example a glass wall. According to a some embodiments, the conveyor 20 transports plates 30 of food directly to where patrons are seated. For example, the seating may be implemented in a typical bar style set-up, wherein the conveyor runs adjacent to the bar. Alternatively, the conveyor may be adapted to transport food in a zig-zag pattern through the tables in the dining area.

In operation, plates of food and drinks are prepared in kitchen 120 and manually placed on the conveyor. Alternatively, the plates may be automatically loaded onto the conveyor, for example using one or more robotic arms. Conveyor 20 transports the food and drinks to the dining area in a direction indicated by arrows 150. Patrons of the restaurant may select individual plates of food and drinks passing through the dining area. Food and drinks that are not selected are transported along the conveyor back into kitchen 120. Such food and drinks may require heating or cooling to maintain a desired temperature range. More particularly, food and drinks that require heating are directed into food heater 40 using diverter 170 and food and drinks that requires cooling are directed into food cooler 100 using diverter 180. Additionally, food and drinks that have been in circulation on the conveyor for greater than a predetermined amount of time or revolutions are directed towards trash area 190 using diverter 200.

In the illustrated embodiment, mounting stations 25 are formed to have a circular shape such that the similarly-shaped plates 30 may be mounted thereon. As would be understood to those of skill in the art, mounting stations 25 and plates 30 may comprise many other shapes without departing from the scope of the present invention. Each plate 30 preferably includes a unique machine-readable identifier 50 such that scanner 60 may determine the type of food disposed thereon. With this information, the system may determine the appropriate price to charge a customer for the plate of food. Also, the system preferably monitors the number and type of foods and drinks that are directed toward trash area 190 such that the kitchen workers know to reduce the preparation of unpopular foods and drinks. According to some embodiments, each mounting station 25 comprises a mounting display for advertising food and drink products. The mounting display may feature a graphical display and sound system that is preprogrammed to promote that type of food or drink disposed on the mounting station.

Referring to FIG. 2, food transport system 10 preferably includes a controller 300 for controlling movement of food. Information may be entered into controller 300 from one or more input devices 310 such as keyboards connected to an input side of controller 300. Controller 300 includes a setting device 320, a detector 330 and a temperature monitor 340. Information obtained by controller 300 may be displayed by one or more monitors 370 disposed in the kitchen area to assist the cooks in determining which food and drinks to prepare.

Setting device 320 is used to set the type of food or drink that is to be served on a respective mounting station 25. In addition, setting device 320 is also used to set the type of food or drink that is to be served on a respective plate 30. Detecting means 330 is used to calculate the circulation time of each plate 30 circulating around conveyor 20 and locate plates 30 whose circulation time exceeds various predetermined time limits for the particular type of food or drink disposed on the plate. For example, when detecting means 330 detects a plate 30 whose circulation time exceeds a predetermined overall time limit, the controller automatically diverts the plate toward trash area 190. More particularly, controller 300 shifts the plate onto trash conveyor 345 using diverter 200.

Temperature monitor 340 is used to check whether the current temperature of each plate falls within a predetermined temperature range for that particular type of food. Certain foods such as dry foods do not require heating or cooling at any time. However, other foods such as hot-served foods and cold-served foods may require heating or cooling, respectively. If the hot food is determined to be too cold, the plate is diverted onto food heating conveyor 350, which passes through food heater 40. Contrariwise, if the cold food is determined to be too warm, the plate is diverted onto food cooling conveyor 360, which passes through food cooler 100. Advantageously, the heating and cooling aspects of the food transport system of the present invention may be used to meet various health code requirements of different countries.

According to some embodiments, some plates 30 include a predetermined heating circulation time or a predetermined cooling circulation time. If one of these circulation times are exceeded, the plate is automatically diverted to be heated or cooled. When detecting means 330 detects a plate 30 whose circulation time exceeds the predetermined heating time limit, the controller automatically diverts the plate onto food heating conveyor 350. Likewise, when detecting means 330 detects a plate 30 whose circulation time exceeds the predetermined cooling time limit, the controller automatically diverts the plate onto food cooling conveyor 360. According to other embodiments, the food transport system comprises more than one full-length conveyor line, for example including a hot line and a cold line, wherein one of the lines is disposed substantially concentrically inside of the other line. In these embodiments, the hot line passes through a food heater that may be used to heat hot-served foods and the cold line passes through a food cooler that may be used to cool cold-served foods.

Referring to FIG. 3, conveyor 20 preferably comprises a motor-driven endless chain 210 that is moved in circulation within a recess 220 between walls 230, which are provided on either side of recess 220. Such conveyors are per se known in the art. A plurality of mounting stations 25 are disposed at predetermined intervals along the endless chain. In operation, food and drinks (e.g., hamburger 250) are prepared in the kitchen and placed on appropriate plates 30. The type of food or drink that is to be served on each plate 30 is associated with machine-readable identifier 50. This information may be changed manually by a user using input device 310. Plates 30 are then placed on appropriate mounting stations 25. The type of food or drink that is to be served on each mounting station 25 is associated with machine-readable identifiers 55. This information may also be changed manually by a user using input device 310.

In some embodiments, each mounting station 25 is further provided with a visual marker 260 that indicates the type of food or drink that is to be served on that particular mounting station 25. In the illustrated embodiment, the visual marker 260 comprises a drawing of the particular food or drink to be served on the mounting station. The visual marker alternatively may comprise one or more words, colors, objects or other visual signs that indicate the appropriate food or drink.

Plates 30 of food and drinks are then placed on the mounting stations based upon the types of food and drinks indicated by visual markers 260. As the plates 30 are conveyed past scanner 60, the machine-readable identifiers on the plate and mounting station are read and the data concerning the start of circulation is automatically entered into controller 300. The information concerning the start of circulation is important for determining when the plate should be heated, cooled or sent to the trash area. Information concerning the start of circulation alternatively may be entered manually into controller 300 via input device 310.

The plates are circulated along conveyor 20 through dining area 110 such that customers may select food and drinks of their choice to be eaten at dining tables 130. Empty mounting bases 25 are conveyed back into the kitchen area where scanner 60 determines that the mounting base is vacant because it does not sense the presence of a machine-readable identifier 50. The scanner then notifies the controller that the appropriate food or drink should be added to the empty mounting base. Controller 300 outputs this information to monitor 370 for display within the kitchen area, thereby notifying the cooks of the types of food and drinks that require replenishing.

Plates 30 that have not been selected are recirculated around the conveyor until they are selected or diverted to be heated, cooled or disposed of. More particularly, when scanner 60 identifies a plate 30 returning to kitchen 120, detecting means 330 automatically calculates the total circulation time of the plate. Controller 300 automatically diverts plates 30 that exceed a predetermined circulation time onto trash conveyor 345. The food and drinks on these plates are discarded in trash area 190 and the plates are removed for washing. In addition, the data concerning circulation time is cleared from controller 300.

After being washed, the plates may be recirculated with fresh food and drinks. The empty mounting station 25 on conveyor 20 eventually reaches scanner 60, which determines that the mounting base is vacant since it does not sense the presence of a machine-readable identifier 50. The scanner then notifies the controller that the appropriate food or drink should be added to the empty mounting base. Controller 300 outputs this information to monitor 370 for display within the kitchen area, thereby notifying the cooks of the types of food and drinks that require replenishing.

Plates 30 returning to kitchen 120 also pass by temperature sensor 70, which determines the current temperature of each plate 30. This data is inputted into the controller such that temperature monitoring means can determine whether the plate requires heating or cooling. Controller 300 automatically diverts food and drinks that require heating into food heater 40 using diverter 170. In addition, controller 300 automatically diverts food and drinks that requires cooling into food cooler 100 using diverter 180.

Referring again to FIG. 1, diverter 170 includes a shaft 380 mounted at one end to a pivot 390. Diverter 170 includes a first position wherein shaft 380 is disposed substantially parallel to conveyor walls 230 and a second position (shown in dotted lines) wherein shaft 380 is disposed at an oblique angle with respect to conveyor walls 230. Similarly, diverter 180 includes a shaft 400 mounted at one end to a pivot 410. Diverter 180 includes a first position wherein shaft 400 is disposed substantially parallel to conveyor walls 230 and a second position(shown in dotted lines) wherein shaft 180 is disposed at an oblique angle with respect to conveyor walls 230. Preferably, diverters 170, 180 are disposed at substantially the same height as plates 30 on the conveyor, but slightly above mounting stations 25. This configuration is preferred so that the diverters may be pivoted to their respective second positions without colliding with a mounting station 25. Diverters 170, 180 include a motorized driving device connected to an output side of controller 300 such that shafts 380, 400 can be pivoted under the direction of controller 300.

When diverters 170, 180 are in the first position, plates 30 that are moving along conveyor 20 are permitted to pass by without being redirected. To redirect a plate 30 onto food heating conveyor 350, controller 300 causes diverter 170 to pivot into the second position. The plate is automatically transferred from mounting station 25 onto a food heating conveyor mounting station 205 under the direction of controller 300. Likewise, to redirect a plate 30 onto food cooling conveyor 360, controller 300 causes diverter 180 to pivot into the second position. The plate is automatically transferred from mounting station 25 onto a food cooling conveyor mounting station 215 under the direction of controller 300. According to some embodiments, robotic arms are provided to permit the plates to be automatically transferred from one conveyor to another. According to other embodiments, the plates may be manually transferred from the one conveyor to another.

With further reference to FIG. 1, diverter 200 includes a shaft 420 mounted at one end to a pivot 430. Diverter 200 includes a first position wherein shaft 420 is substantially parallel to conveyor walls 230 and a second position (shown in dotted lines) wherein shaft 420 is at an oblique angle with respect to conveyor walls 230. To redirect a plate 30 onto trash conveyor 345, controller 300 causes diverter 200 to pivot into the second position. The plate is automatically transferred from mounting station 25 onto a trash conveyor mounting station 225 under the direction of controller 300. Alternatively, the plates may be manually transferred onto the trash conveyor. Diverter 200 also includes a motorized driving device connected to an output side of controller 300 such that shaft 420 can be pivoted under the control of controller 300.

Referring to FIGS. 4A and 4B, a preferred embodiment for food heater 40 will now be described. Food heater 40 comprises a steamer 440 adapted to heat hot-served foods (e.g., hamburger 250) that have been circulating on the conveyor for more than a predetermined amount of time. Steamer 440 is in fluid communication with a boiler 450, which provides the requisite steam to heat the food. Steam enters the steamer by way of a steam inlet 460. According to other embodiments of the present invention, food heater may comprise other types of heaters, including, but not limited to, microwave ovens, heat lamps and roasters without departing from the scope of the present invention. Of course, as would be understood to those of skill in the art, food heater 40 may be positioned at other positions around the conveyor 20 without departing from the scope of the present invention.

In the illustrated embodiment, steamer 440 includes a front sliding door 470 and a rear sliding door 480, both of which are dimensioned for the passage of plates 30 moving on food heating conveyor 350. Sliding doors 470, 480 are adapted to move up and down as indicated by arrows 490 between open and closed positions. Sliding doors 470, 480 also include a motorized driving device connected to an output side of controller 300 such that opening and closing of the doors is controlled by controller 300. Plates 30 of food enter the steamer through an front opening 500 in the steamer, which is formed when front sliding door 470 is in the open position. Food heating conveyor 350 preferably is disposed beneath the steamer such that only the plates disposed on top of conveyor 20 enter the steamer through opening 500.

After a plate 30 enters through opening 500, front sliding door 470 is automatically closed and a blast of steam is delivered from boiler 450. The plate continues to move through the steamer while it is being heated by the blast of steam. According to some embodiments, the plate of food remains in the steamer for approximately 5-15 seconds. Of course, as would be understood by those of skill in the art, plates may remain in the steamer for longer or shorter durations without departing from the scope of the present invention. According to other embodiments, plates that enter the steamer are removed from the conveyor one after another until a plurality of plates 30 are disposed within the steamer. At this point, the boiler provides a steam blast that heats all of the food and drinks disposed within steamer 440.

With further reference to FIGS. 4A and 4B, after the plate of food is heated within steamer 440, the rear sliding door is automatically opened by the controller, thereby permitting the plate to exit the steamer through a rear opening 510 as the plate continues along food heating conveyor 350. In a preferred embodiment, the controller controls the speed of the food heating conveyor such that the plate is automatically transferred from a food heating conveyor mounting station 205 to its original mounting station 25 on conveyor 20. According to other embodiments, the transfer of the plate from the food heating conveyor onto conveyor 20 may be performed manually.

Referring to FIGS. 5A and 5B, a preferred embodiment for food cooler 100 will now be described. Food cooler 100 comprises a freezer 540 adapted to cool cold-served foods (e.g., salad 545) that have been circulating on the conveyor for more than a predetermined amount of time. Freezer 540 is in fluid communication with a refrigerator 550, which provides refrigerant or coolant to cool the food. Refrigerant enters the freezer by way of a refrigerant inlet 560. As would be understood to those of skill in the art, food cooler 100 may be positioned at other positions around the conveyor 20 without departing from the scope of the present invention.

In the illustrated embodiment, freezer 540 includes a front sliding door 570 and a rear sliding door 580 dimensioned for the passage of plates 30 moving on food cooling conveyor 360. Sliding doors 570, 580 are adapted to move up and down as indicated by arrows 590 between open and closed positions. Sliding doors 570, 580 also include a motorized driving device connected to an output side of controller 300 such that opening and closing of the doors is controlled by controller 300. Plates 30 of food enter the freezer through an front opening 600 in the freezer, which is formed when front sliding door 570 is in the open position. Food cooling conveyor 360 preferably is disposed beneath the freezer such that only the plates disposed on top of conveyor 20 enter the steamer through opening 500.

After a plate 30 enters through opening 600, front sliding door 570 is automatically closed and a blast of refrigerant is delivered from refrigerator 550. The plate continues to move through the freezer while it is being cooled by the blast of refrigerant. According to some embodiments, the plate of food remains in the freezer for approximately 5-15 seconds. Of course, as would be understood by those of skill in the art, plates may remain in the freezer for longer or shorter durations without departing from the scope of the present invention. According to other embodiments, plates that enter the freezer are removed from the conveyor one after another until a plurality of plates 30 are disposed within the freezer. At this point, the refrigerator provides a refrigerant blast that cools all of the food and drinks disposed within freezer 540.

With further reference to FIGS. 5A and 5B, after the plate of food is cooled within freezer 540, the rear sliding door is automatically opened by the controller, thereby permitting the plate to exit the freezer through a rear opening 610 as the plate continues along food cooling conveyor 360. In a preferred embodiment, the controller controls the speed of the food cooling conveyor such that the plate is automatically transferred from a food cooling conveyor mounting station 215 to its original mounting station 25 on conveyor 20. According to other embodiments, the transfer of the plate from the food cooling conveyor onto conveyor 20 may be performed manually.

Thus, it is seen that a food heating and transport system is provided. One skilled in the art will appreciate that the present invention can be practiced by other than the various embodiments and preferred embodiments, which are presented in this description for purposes of illustration and not of limitation, and the present invention is limited only by the claims that follow. It is noted that equivalents for the particular embodiments discussed in this description may practice the invention as well. 

1. A food transport system, comprising: a conveyor including a plurality of mounting stations for mounting individual plates of food; a controller that controls the movement of food around the conveyor; and a temperature sensor that senses the temperature of the individual plates of food; wherein the controller includes a temperature monitor that checks whether individual plate of food fall within a predetermined temperature range.
 2. The food transport system of claim 1, wherein the controller diverts individual plates of food to a food heater if they have a temperature that is below the predetermined temperature range.
 3. The food transport system of claim 1, wherein the controller diverts individual plates of food to a food cooler if they have a temperature that is above the predetermined temperature range.
 4. The food transport system of claim 1, further comprising a unique machine-readable identifier disposed on each plate of food.
 5. The food transport system of claim 4, further comprising a unique machine-readable identifier disposed on each mounting station.
 6. The food transport system of claim 5, further comprising one or more scanners for reading the machine-readable identifiers.
 7. The food transport system of claim 2, wherein the food heater is a steam heater.
 8. The food transport system of claim 2, wherein the food heater is chosen from the group consisting of microwave ovens, heat lamps and roasters.
 9. The food transport system of claim 1, wherein the controller further comprises a setting device, wherein the setting device is used to set the type of food to be served on individual plates and mounting bases.
 10. The food transport system of claim 1, wherein the controller further comprises a detecting means that detects plates of food having circulation times that exceed a predetermined time limit.
 11. The food transport system of claim 10, wherein plates of food having circulation times that exceed the predetermined time limit are diverted onto a trash conveyor.
 12. The food transport system of claim 1, wherein each mounting station includes a visual marker that indicates the type of food to be served thereon.
 13. The food transport system of claim 1, wherein the controller outputs information concerning the types of food that requires replenishing to a monitor located in a food preparation area.
 14. The food transport system of claim 2, wherein the food heater includes a front door and a rear door, which are dimensioned for the passage of individual plates of food.
 15. The food transport system of claim 14, wherein opening and closing of the front and rear doors is controlled automatically by the controller.
 16. A food transport system, comprising: a conveyor; a plurality of individual plates of food positioned along the conveyor; a controller that controls the movement of food around the conveyor; and wherein the controller includes a detecting means that determines the circulation time of each plate of food.
 17. The food transport system of claim 16, wherein the controller diverts individual plates of food to a food heater if they have a circulation time that exceeds a predetermined heating circulation time limit.
 18. The food transport system of claim 16, wherein the controller diverts individual plates of food to a food cooler if they have a circulation time that exceeds a predetermined cooling circulation time limit.
 19. The food transport system of claim 16, wherein the controller diverts individual plates of food to a trash area if they have a circulation time that exceeds a predetermined overall circulation time limit.
 20. The food transport system of claim 16, further comprising a unique machine-readable identifier disposed on each plate of food.
 21. The food transport system of claim 20, further comprising one or more scanners for reading the machine-readable identifiers.
 22. The food transport system of claim 17, wherein the food heater is a steam heater.
 23. The food transport system of claim 17, wherein the food heater is chosen from the group consisting of microwave ovens, heat lamps and roasters.
 24. The food transport system of claim 16, wherein the controller further comprises a setting device, wherein the setting device is used to set the type of food to be served on individual plates.
 25. The food transport system of claim 16, wherein the controller outputs information concerning the types of food that requires replenishing to a monitor located in a food preparation area.
 26. The food transport system of claim 17, wherein the food heater includes a front door and a rear door, which are dimensioned for the passage of individual plates of food.
 27. The food transport system of claim 26, wherein opening and closing of the front and rear doors is controlled automatically by the controller. 